I had a massive stroke a year ago and lately i've been forgetting a lot is that normal.

Maybe: Vascular dementia is the result of strokes, sometimes smaller ones that aren't noticed until the end damage accrues. This could be a reason, but it is important you get evaluated for other, reversible causes of mental status change.

Yes: After a stroke it is not unusual to have cognitive issues. It also depends on where the stroke occurred. That said, there may be other things going on such as sleep problems, stress, not enough exercise and nutrition issues. Those are good things to look at because these are fixable. See your doctor and start looking into this issue.

Not unexpected: Note that you are quite young for massive stroke, and if not due to arterial dissection, or other trauma, may well be of value to search for causation like cardiac pfo, anti-phopholipid antibody syndrome, homocysteinuria, mthfr mutations. Depending on extent and location, cognitive issues do occur, and may respond to drugs such as donepezil or galantamine (galantamine hydrobromide).