I recommend you take your blood pressure (hopefully you have a home monitor). If it's been a couple hours from when you normally take your pill, the pill should be working and your blood pressure should look like the pill is doing its job. But if your blood pressure is very high when you take it whereas it is normally normal with medication, it's a strong possibility you skipped taking it.
If you normally take this medication in the morning and your blood pressure is not sky high, just wait until tomorrow and take it at the normal time. If your blood pressure is a little elevated, take a ten minute walk to help bring it down. Or, if it doesn't upset you to do deep breathing, try that for ten minutes as an alternative. Which ever you try, walking or deep breathing, try taking your blood pressure afterward and see if it hasn't come down. And take your dose at the usual time tomorrow.
It's often hard to remember if one took their medicine or not as memory starts to worsen. I have family who use those pill holders that have the days of the week listed on it. There are ones that have different times of day as well as the days of the week. I recommend you get one from you local pharmacy and lay out your blood pressure medication in it for each day. That way, like a parent of mine has done, you can look at your container and discover whether or not you forgot to take your pill.
Missing a day won't hurt, just don't miss it tomorrow.